TM 11-6625-3081-231-21. ELECTRONIC STATION (cont)1-21(3) ProgrammerCCAsThe four programmer CCAs are plugged into the backplane andreceive digital input signals in the form of hexadecimal data bytes.Since the cir-cuitry in the four programmer CCAs are identical, the following description applies toall.A total of nine data bytes, plus a data transfer strobe following each byte,constitutes a complete instruction sequence.(a) The first three data lines and the address select switches are monitoredby the card address detector.If the content of the three data lines and the switchpositions coincide, the card address is correct and the MCA signal is applied to thecontrol logic.If the subsequent incoming signal is identified as the ASCII character"=" on its separate line, the control circuit enables the transfer of the next sevendata bytes, as well as a shift and a latch signal, across the opto-isolators.(b) The data bytes are now entered into the shift registers by means of theshift command, which enables the shift registers until all seven data bytes areplaced.Following the last data byte, the latch command strobes the parallel datainto the latches.The data bytes representing the channel A and channel B fields areapplied to the digital to analog converters (DAC-A, DAC-B), while the range andpolarity byte is transferred to the control circuits within the programmable ampli-fiers to establish the amplifier polarity and output ranges. Channel A supplies O to± 10 volts, with reference to analog common, andwith reference to analog common, to programmabled. PROGRAMMABLE POWER SUPPLY ASSEMBLY 1A3(1) General.The programmable power supplyChannel-B supplies O to ± 1 volt,power supply assembly 1A3.assembly 1A3 (FO-5) consists of fourpower supplies (PS1-PS4). PS1 and PS2 are adjustable form O-36 vdc output. PS3 andPS4 are adjustable from O-75 vdc output.Refer to FO-9 for dc power distributiondiagram.Circuits of the four power supplies are identical, therefore the followingdescription applies to all.The power supply is basically a voltage and current sta-bilized dc source with a sharp crossover between the voltage and current mode of oper-ation,A linear series pass element is controlled by either the current control chan-nel or the voltage control channel.The operating mode is determined by the value ofthe front panel adjusted (or externally controlled) output voltage and output current,and by the magnitude of the load resistance.(2) VoltageMode.In the voltage mode of operation, the voltage comparatoramplifier senses any change in the output voltage by comparing it to a referencepotential, developed by the voltage control amplifier. When a change is detected, anerror signal is amplified and becomes a control signal for the driver stage.Thecontrol signal is applied, via the driver stage, to the pass element which increasesor decreases its conductance in response to the driver signal as required to maintainthe output voltage at the desired value.1-132